Many new emerging applications require the use of ultra-low power consumption solutions inside a chip. This will allow them to be incorporated into devices that operate from a small non-chargeable battery for very long periods without the need to frequently charge the battery. For example, wearable devices, mobile devices and IoT (Internet of Things) devices may require an ultra-low power design flow.
Sub-threshold technology is a way of operating the CMOS transistors using an operating voltage which is below their threshold voltage (known as VT), which is the point where the transistor moves from the weak inversion state, where the transistors are never fully turned on, to the strong inversion state where the transistor are fully turn on. When operating in the sub-threshold region, the transistor state varies between being fully turned off and partially turned on.
Near-threshold technology is the way of operating the CMOS transistor using an operating voltage which is a slightly above the threshold point where the transistor moves to the strong inversion state but still working slower than using high voltages which are above this point.
Near-threshold and Sub-threshold technologies are considered to be the most energy-efficient solution for low power applications where area and performance is of secondary importance.
When operating in the Near-threshold or Sub-threshold region, transistors operate at a lower voltage and by such operation the transistor uses less power. When using this operation voltage range both, dynamic power and static power are reduced. Dynamic power is a ratio of the operating voltage by a power of two, and static power is a ratio of the operating voltage, therefore reducing the operating voltage of the device to a Sub-threshold voltage level will reduce the consumed power dramatically.
Therefor there is a need for technology that can operate the transistor at the Near-threshold or Sub-threshold voltage domains and still be reliable and give good performance.